IF Sampling Scheme for DSP-Friendly Digital Radio Conversion
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Solution Overview
Problem
Current digital radio systems face challenges in handling high data rates from oversampled intermediate frequency signals, making it difficult to perform baseband conversion using off-the-shelf digital signal processing circuitry.
Innovation Solution
A digital radio system employs a mixer and an analog-to-digital converter that generates an intermediate frequency signal and quantizes it using a sampling frequency greater than twice the signal's bandwidth but less than the intermediate frequency, allowing for baseband conversion without complex frequency mixing, reducing computing power and enabling implementation with standard DSP components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oversampling is used to digitize the intermediate frequency signal at a high rate, then signal accuracy is improved, but the data rate becomes too high for off-the-shelf digital signal processing circuitry to handle
Solution Approach 1:
The patent changes the sampling frequency parameter to a specific value (1.920 MHz) that satisfies the Nyquist criterion for the signal bandwidth while being less than the intermediate frequency. This parameter selection enables both adequate signal accuracy and a manageable data rate that can be processed by standard DSP circuitry.
2Measurement precision
If complex frequency mixing is used to perform baseband conversion, then conversion accuracy is improved, but computing power requirements increase
Solution Approach 1:
The patent changes the sampling frequency to a specific value (1.920 MHz) that is an integer multiple of standard audio sample rates. This parameter change enables the use of simple multiplication operations for baseband conversion instead of complex frequency mixing, significantly reducing computing power requirements while maintaining conversion accuracy.
Solution Approach 2:
The patent replaces complex frequency mixing operations with simple multiplication operations. This substitution reduces the computational complexity from what would require complex hardware mixing to straightforward digital multiplication that can be efficiently performed by off-the-shelf DSP circuitry.
3Productivity
If high computing power is used in digital signal processing, then processing capability is improved, but power consumption increases
Solution Approach 1:
The patent selects a sampling frequency (1.920 MHz) that is an integer multiple of standard audio sample rates like 48 kHz or 44.1 kHz. This parameter selection enables the use of efficient processing algorithms that maintain high processing capability while minimizing power consumption in the DSP circuitry.
Solution Approach 2:
The patent replaces computationally intensive operations with simpler multiplication operations, thereby reducing the processing power required and consequently lowering the power consumption of the digital signal processing circuitry while maintaining adequate processing capability.
Data Source
AI summary
A digital radio system comprises a mixer and an analog-to-digital converter communicative coupled to the mixer. The mixer generates an intermediate frequency signal based at least in part upon a radio frequency signal and a local oscillator signal, wherein the intermediate frequency signal comprises a signal of interest having a particular bandwidth. The analog-to-digital converter generates a digital signal by quantizing the intermediate frequency signal using a sampling frequency that is greater than twice the bandwidth of the signal of interest and less than the frequency of the intermediate frequency signal.